This project is designed to evaluate the interrelationships between the microbial community and pollutants in the New Bedford Harbor area, an EPA designated Superfund Site, and obtain a comprehensive evaluation of the health of the ecosystem. This project will build on an extensive database obtained in the first three years of our nIEHS sponsored superfund project, designed to measure the distribution and transport of toxic metals throughout the New Bedford Harbor area. This next phase of the research is divided into three parts: bioavailability and bioaccumulation rates of contaminants, effect of remediation efforts on the ecosystem health, and the development of a "microbial community biomarker" of environmental stress. Part one will extend current research on metal fluxes from sediments and address subsequent bioavailability of toxic metals to the biota and bioaccumulation through the food chain, from sediment invertebrates through the crustacea to the edible species, particularly the economically important Winter Flounder. Part two will examine contaminant plumes released from dredging activity and closely monitor the effect on the biota at specific locations. This will include an evaluation of the effects of remediation on New Bedford Harbor salt marshes. Salt marsh ecology would be expected to responds rapidly to changes in ecosystem health. The third part is designed to characterize the microbial communities from polluted and clean sites both microbiologically and genetically. This research is designed primarily to produce microbial ecosystem parameters that can be considered biomarkers of environmental stress.